Heat Exchange System

ABSTRACT

A heat exchange system operating on a vapor compression cycle is capable of operating in both an air conditioning mode and a heat pump mode. The heat exchange system can include a parallel flow heat exchanger that operates as a condenser in one mode and as an evaporator in the other mode. The heat exchanger can include a first, second, and third fluid manifold, with fluid conduits connecting the first and second fluid manifolds, and with additional fluid conduits connecting the second and third fluid manifolds. The heat exchanger can be configured to transfer heat between a working fluid traveling through the fluid conduits and another fluid, such as an air flow passing over the fluid conduits.

FIELD OF THE INVENTION

The present invention relates to the field of vapor compression heat exchange systems, particularly for heating and cooling spaces.

SUMMARY

In some embodiments of the invention, a heat exchange system operating on a vapor compression cycle and capable of operating in both an air conditioning mode and a heat pump mode is provided. The heat exchange system can include, in at least some embodiments, a parallel flow heat exchanger that operates as a condenser in one mode and as an evaporator in the other mode. The heat exchanger can have a first, second, and third fluid manifold, with fluid conduits connecting the first and second fluid manifolds, and with additional fluid conduits connecting the second and third fluid manifolds. The heat exchanger can be configured to transfer heat between a working fluid traveling through the fluid conduits and another fluid, such as an air flow passing over the fluid conduits.

In at least some embodiments, the heat exchange system is configured so that the fluid conduits connecting the first and second manifolds and the fluid conduits connecting the second and third fluid manifold are fluidly in series with respect to the working fluid flow therethrough when the heat exchanger is operated as a condenser, and are fluidly in parallel with respect to the working fluid flow therethrough when the heat exchanger is operated as an evaporator.

In some embodiments the parallel flow heat exchanger includes a fluid flow distribution device within the second fluid manifold, wherein the fluid flow distribution device is operable to distribute a low pressure two-phase working fluid to a set of fluid conduits when the heat exchanger is operated as an evaporator, and is bypassed or substantially bypassed by the working fluid when the heat exchanger is operated as a condenser.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a heat exchange system according to an embodiment of the present invention.

FIG. 2 is the schematic of FIG. 1 showing refrigerant flow through the system when the system is operating in a first mode.

FIG. 3 is the schematic of FIG. 1 showing refrigerant flow through the system when the system is operating in a second mode.

FIG. 4 is a perspective view of a portion of a parallel flow heat exchanger for use in some embodiments of the invention.

FIG. 5 is an exploded perspective view of a portion of a parallel flow heat exchanger for use in some embodiments of the invention.

FIG. 6A is a sectioned side view of a portion of a parallel flow heat exchanger for use in some embodiments of the invention.

FIG. 6B is a perspective view of the distribution tube illustrated in FIG. 6A.

FIG. 7 is a perspective view of a parallel flow heat exchanger for use in some embodiments of the invention.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

FIGS. 1-3 illustrate a heat exchange system 1 according to some embodiments of the present invention. In some embodiments, including the illustrated embodiment of FIGS. 1-3, the heat exchange system 1 is a vapor compression system operable in a first mode to transfer heat from a conditioned space to a relatively cool and relatively low-pressure working fluid, and to reject the heat from the working fluid after the working fluid has been compressed to a relatively hot and relatively high-pressure state. The embodiment shown in FIGS. 1-3 is furthermore operable in a second mode to transfer heat to a conditioned space from a relatively hot and relatively high-pressure working fluid, that heat having been transferred to the working fluid from a non-conditioned space while the working fluid was in a relatively cold and relatively low-pressure state, wherein the working fluid has subsequently been compressed to the relatively hot and relatively high-pressure state. The heat exchange system 1 can be used for a wide variety of applications, such as, for example, electronics cooling, industrial equipment thermal management, vehicular applications, and the like.

When reference is made herein to the working fluid of the vapor compression system, it should be understood that the working fluid can consist of any fluid capable of being used in a vapor compression cycle, including but not limited to refrigerants (such as R12, R22, R134a, R410a, and the like), organic refrigerants, ammonia, and CO₂.

In some applications, heat transferred to the working fluid can be transferred from another fluid such as air, water, coolant, exhaust gas, an organic refrigerant, and the like. Likewise, in some applications, the heat rejected from the working fluid can be transferred to another fluid such as air, water, coolant, exhaust gas, an organic refrigerant, and the like.

Referring to FIG. 1, an embodiment of the heat exchange system 1 comprises a compressor 2, a 4-way valve 3, an expansion device 4, a first heat exchanger 5, and a second heat exchanger 16. By way of example only, the first heat exchanger 5 is of a type known as a parallel flow heat exchanger, in which a first fluid travels through a plurality of fluid conduits 9 arranged in parallel while a second fluid travels over the plurality of fluid conduits 9, the first and second fluids being thereby placed in heat transfer relation with one another. It should be understood by one having skill in the art that the term “parallel flow heat exchanger” refers to the heat exchanger having a plurality of fluid conduits that allow for the first fluid to be distributed therein so that the portion of the first fluid in one of the plurality of fluid conduits is flowing in parallel with the portions of the first fluid in the other of the plurality of fluid conduits. A heat exchanger of this type can further have additional fluid conduits for the first fluid which are not in parallel with the plurality of fluid conduits.

In any case, the second fluid flow can flow over the fluid conduits 9 so as to be in a crossflow orientation to the first fluid flow, can flow over the fluid conduits 9 so as to be in a counterflow orientation to the first fluid flow, can flow over the fluid conduits 9 so as to be in a parallel flow orientation to the first fluid flow, or can flow over the fluid conduits in any combination thereof.

Referring again to FIG. 1, the heat exchanger 5 is shown to comprise a first fluid manifold 6, a second fluid manifold 7, a first plurality of parallel fluid conduits 9 a fluidly connecting the first fluid manifold 6 to the second fluid manifold 7, a third fluid manifold 8, and a second plurality of parallel fluid conduits 9 b fluidly connecting the third fluid manifold 8 to the second fluid manifold 7.

The illustrated heat exchanger 5 further comprises a port 10 opening to the first fluid manifold 6, a port 11 opening to the second fluid manifold 7, and a port 12 opening to the third fluid manifold 8. In some embodiments, the number of fluid conduits 9 a can be equal to the number of fluid conduits 9 b, while in other embodiments the number of fluid conduits 9 a can be greater than or less than the number of fluid conduits 9 b.

Still with reference to FIG. 1, the illustrated heat exchange system 1 is configured so that a first port 31 of the heat exchanger 16 is fluidly connected to a first port 29 of the expansion device 4, and a second port 32 of the heat exchanger 16 is fluidly connected to a first port 25 of the 4-way valve 3. A second port 30 of the expansion device 4 is fluidly connected to the port 11 of the heat exchanger 5 by way of a first check valve 13, the check valve 13 being configured to allow fluid flow from the port 30 of the expansion device 4 to the port 11 of the heat exchanger 5, but to not allow fluid flow from the port 11 of the heat exchanger 16 to the port 30 of the expansion device 4. The port 30 is additionally fluidly connected to the port 12 of the heat exchanger 5 by way of a second check valve 14, the check valve 14 being configured to allow fluid flow from the port 12 of the heat exchanger 5 to the port 30 of the expansion device 4, but to not allow fluid flow from the port 30 of the expansion device 4 to the port 12 of the heat exchanger 5.

Still with reference to FIG. 1, the heat exchange system 1 is furthermore configured so that the compressor 2 has a suction side fluidly connected to a second port 26 of the 4-way valve 3, and a discharge side fluidly connected to a third port 27 of the 4-way valve 3. A fourth port 28 of the 4-way valve 3 is fluidly connected to the port 10 of the heat exchanger 5. The fourth port 28 is additionally fluidly connected to the port 12 of the heat exchanger 5 by way of a third check valve 15, the third check valve 15 being configured to allow fluid flow from the port 12 of the heat exchanger 5 to the fourth port 28 of the 4-way valve 3, but to not allow fluid flow from the fourth port 28 of the 4-way valve to the port 12 of the heat exchanger.

FIG. 2 shows the heat exchange system 1 operating in a first mode, with arrows 33 indicating the flow of working fluid through the system. In this mode of operation, the 4-way valve 3 is set so as to direct working fluid from the port 27 to the port 25, so that hot pressurized working fluid exiting the discharge side of the compressor 2 is directed to enter the heat exchanger 16 through port 32. Heat is rejected from the working fluid in the heat exchanger 16, and the cooled pressurized working fluid exits port 31 to enter the expansion device 4 through port 29. The working fluid is expanded to a cold, low pressure two-phase fluid in the expansion device 4, and exits through the port 30. The working fluid then passes through the check valve 13 and enters the manifold 7 of the heat exchanger 5 through the port 11. The working fluid exiting the expansion device 4 is prevented from bypassing the heat exchanger 5 by the check valve 14.

Within the heat exchanger 5 a first portion of the working fluid flows from manifold 7 to manifold 6 through the first plurality of fluid conduits 9 a, while the remainder of the working fluid flows from manifold 7 to manifold 8 through the second plurality of fluid conduits 9 b. The amount of fluid flowing through the plurality of fluid conduits 9 a can be equal to, more than, or less than the amount of fluid flowing through the plurality of fluid conduits 9 b. Heat is transferred into the working fluid as it flows through the tubes 9, thereby vaporizing at least some of the liquid portion of the working fluid to a vapor, and possibly partially superheating the vapor working fluid. The first portion of the working fluid exits the heat exchanger 5 through the port 10 and is rejoined by the remainder of the working fluid exiting the heat exchanger 5 through the port 12 and passing through the check valve 15. The recombined working fluid enters the 4-way valve 3 through port 28, where it is directed to exit the 4-way valve 3 through port 26, after which it enters the suction side of the compressor 2 in order to be compressed to a hot pressurized working fluid for repeating the above-described cycle.

FIG. 3 shows the heat exchange system 1 operating in a second mode, with arrows 34 indicating the flow of working fluid through the system. In this mode of operation, the 4-way valve 3 is set to direct working fluid from the port 27 to the port 28, so that hot pressurized working fluid exiting the discharge side of the compressor 2 is directed to enter the heat exchanger 5 through port 10. The working fluid exiting the port 28 is prevented from entering the heat exchanger 5 through the port 12 by the check valve 15. After entering the heat exchanger 5 through port 10, the working fluid passes from the manifold 6 to the manifold 7 through the first plurality of fluid conduits 9 a where the working fluid rejects some quantity of heat as it passes through the fluid conduits 9 a. The working fluid in the manifold 7 is prevented from exiting through the port 11 by the check valve 14. Within the manifold 7, the working fluid is distributed to the second plurality of fluid conduits 9 b, where the working fluid rejects some quantity of heat as it passes therethrough and flows to the manifold 8. The working fluid exits the heat exchanger 5 through the port 12 and flows to the port 30 of the expansion device 4 through the check valve 14.

With continued reference to FIG. 3, the working fluid is then expanded to a cold, low pressure two-phase fluid in the expansion device 4, and exits through the port 29. The working fluid exiting the port 29 enters the heat exchanger 16 through the port 31. Heat is transferred into the working fluid as it flows through the heat exchanger 16, thereby vaporizing at least some of the liquid portion of the working fluid to a vapor, and possibly partially superheating the vapor working fluid. The working fluid exits the heat exchanger 16 through the port 32, and is directed to enter the 4-way valve 3 through the port 25. The working fluid exits the 4-way valve 3 through the port 26 and enters the suction side of the compressor 2 in order to be compressed to a hot pressurized working fluid for repeating the above-described cycle.

In some embodiments, the heat exchanger 5 is an indoor heat exchanger configured to transfer heat between a refrigerant passing through the fluid conduits 9 and an air flow directed to enter a conditioned space, and the heat exchanger 16 is an outdoor heat exchanger configured to transfer heat between the outside ambient and a refrigerant passing through the heat exchanger 6, so that the first mode of operation of the heat exchange system 1 is an air conditioning mode and the second mode of operation of the heat exchange system 1 is a heat pump mode.

Although the heat exchanger 5 is shown in FIGS. 1-3 as having a single inlet 11, it will be recognized by those skilled in the art of designing evaporative parallel flow heat exchangers that it can be advantageous to have multiple ports 11 in order to better distribute working fluid into the flow manifold 7. In recognition thereof, no limitation on the number of inlet ports 11 is intended or implied unless specifically stated in the description of a given embodiment herein. Some specific embodiments of a parallel flow heat exchanger especially well-suited for use as a heat exchanger 5 in a heat exchange system 1 according to the present invention will now be discussed, with reference made to FIGS. 4-7.

FIG. 4 shows a fluid conduit 9 for use in some embodiments of the parallel flow heat exchanger 5, the fluid conduit comprising an elongated flattened tube 22 with a plurality of internal webs 23, the webs 23 serving to divide the internal volume of the tube 22 into a plurality of parallel flow channels 24. In a preferred embodiment, the flow channels 24 have a hydraulic diameter within a range known to be advantageous for evaporative heat exchangers, such as for example, a range of 0.5 mm to 1.5 mm. In addition to providing a preferred hydraulic diameter for the flow channels 24, the webs 23 can also provide an extended heat transfer surface area for the fluid flowing through the conduit 9, and can also provide structural reinforcement to the tube 22.

In some embodiments, the webs 23 can be integral to the tube 22, such as by being formed by extruding the tube 22 along with the webs 23. In other embodiments, the webs 23 can be added to the tube 22 by forming the webs 23 out of a convoluted sheet, inserting the convoluted sheet into the tube 22, and brazing the crests of the convolutions to the inner walls of the tube 22 in order to form the webs. In some embodiments, the tube 22 can be formed from a single strip of material that is bent into the shape of the tube 22 and is sealed by welding, brazing, or any other suitable process. In other embodiments, the tube 22 can be formed from two or more strips of material that are bent and assembled to form the tube 22, the joints between the two or more strips being sealed by welding, brazing, or any other suitable process. In some embodiments, the webs 23 can be formed from a convoluted segment of one or more strips of material that partially or wholly comprise the tube 22.

The geometry of the flow channels 24 can vary depending at least in part upon the specific application or the construction methods used to form the tube 22 and webs 23. For example, and without limitation, the flow channels 24 can have a triangular, square, circular, oval, hexagonal, or other geometric shape.

The embodiment of FIG. 4 further shows extended surfaces 17 attached to outer surfaces of the tube 22 in order to provide heat transfer surface area enhancement. In some embodiments, the extended surfaces 17 can be formed from convoluted sheets of material, the crests of which are bonded to outer surfaces of a tube 22 in any suitable manner, such as by brazing. In some such embodiments, the extended surfaces 17 can span the distance between two adjacent tubes 22, and can have crests that are bonded to both of the tubes 22. In certain other embodiments, the extended surfaces 17 can be formed of a plurality of individual plate fins having slots or notches to allow the tubes 9 to pass through the plate fins.

Turning now to FIG. 5, in some embodiments the manifold 8 of the heat exchanger 5 of a heat exchange system 1 according to the present invention can comprise a cylindrical header tube 18 having a plurality of slots 20 to receive a plurality of the tubes 22, each tube 22 comprising a fluid conduit 9 for the refrigerant flow. For simplicity, only a single slot 20 and corresponding tube 22 are shown in FIG. 5, but it is to be understood that the slots 20 and tubes 22 would be repeated along the length of the header tube 18 in order to form the plurality of parallel flow conduits 9 b. An end portion of the tube 22 is received into the header tube 18 and is sealed thereto by welding, brazing, gluing, or in any other suitable manner to allow for the working fluid to flow between the channels 24 within the tube 22 and the manifold 8 without leakage of the working fluid. A similar manner of construction can be used to construct the manifold 6 and its connection to the plurality of fluid conduits 9 a, as well as to construct the manifold 7 and its connection to the plurality of fluid conduits 9 a and 9 b.

In some embodiments, the manifolds 6 and 8 can be constructed of a single header tube 18, the header tube 18 having a slot 21 to receive a baffle 19 separating the header 18 into a flow manifold 6 on one side of the baffle 19 and a flow manifold 8 on the other side of the baffle 19.

In some embodiments of the heat exchanger 5, such as the embodiment shown in FIGS. 6A, 6B and 7, the manifold 7 can contain a distribution tube 33 having an internal volume 34 which is fluidly connected to the one or more ports 11, so that when the system 1 is operating in the first operating mode (see FIG. 2), the working fluid enters the heat exchanger 5 by passing from the ports 11 to the volume 34. The distribution tube 33 can include a plurality of distribution holes 35 located along the length of the distribution tube, wherein the holes 35 enable the working fluid to pass from the volume 34 inside the distribution tube 33 to a volume 36 located within the manifold 7 but external to the distribution tube 33. In such embodiments, the volume 36 is in fluid communication with the channels 24 located within the fluid conduits 9. When the system 1 is operating in the second mode of operation (see FIG. 3), the working fluid exits the first plurality of fluid conduits 9 a, enters the volume 36 located within the manifold 7, and is able to travel through the volume 36 to enter the second plurality of fluid conduits 9 b.

In some embodiments including a distribution tube 33 as described above, the holes 35 can be sized so that the pressure drop incurred by the working fluid as it passes from the volume 34 to the volume 36 is substantially greater than the pressure drop incurred by the working fluid as it travels through the volume 34. This will force the amount of the working fluid passing through each of the distribution holes 35 to be approximately equal, thereby ensuring an approximately uniform distribution of fluid flow to the fluid conduits 9. As is well-known in the art of parallel flow evaporative heat exchangers, the performance of such heat exchangers can be greatly improved by maximizing uniformity of the flow of fluid to each of the parallel conduits.

In some embodiments, the heat exchanger 5 can be of a construction and design as disclosed in commonly assigned U.S. Pat. No. 7,921,904 issued Apr. 12, 2011 and entitled “HEAT EXCHANGER AND METHOD”, the disclosure of which is herein incorporated by reference in its entirety. One such an embodiment of a heat exchanger 5, illustrated in FIG. 7, includes a tube 18 comprising the manifolds 6 and 8 separated by a baffle 19, and further includes a tube 37 comprising the manifold 7 located adjacent the tube 18. The fluid conduits 9 extend from the manifolds 6 and 8 to the manifold 7 via several straight sections of the conduits 9 interconnected by a bent or folded sections of the conduits 9. The illustrated embodiment of FIG. 7 further includes a distribution tube 33 located within the manifold 7 and extending through the end caps 38 closing off either end of the tube 37, wherein the ends of the distribution tube 33 extend through the end caps 38 defining the inlet ports 11.

Various alternatives to features, elements, and manners of operation of the present invention are described herein with reference to specific embodiments of the present invention. However, with the exception of features, elements, and manners of operation that are mutually exclusive of or are inconsistent with each embodiment described above, it should be noted that alternative features, elements, and manners of operation described with reference to one particular embodiment are applicable to the other embodiments.

Various alternatives to the certain features and elements of the present invention are described with reference to specific embodiments of the present invention. With the exception of features, elements, and manners of operation that are mutually exclusive of or are inconsistent with each embodiment described above, it should be noted that the alternative features, elements, and manners of operation described with reference to one particular embodiment are applicable to the other embodiments.

The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention. 

What is claimed is:
 1. A heat exchange system capable of operating both an air conditioning mode and a heat pump mode, comprising: a compressor operable to compress and circulate a refrigerant through the heat exchange system; an expansion device operable to expand the refrigerant from a high pressure liquid state to a low pressure two-phase state; a reversing valve operable to direct the flow of refrigerant through the heat exchange system, the reversing valve having a first port fluidly connected to an inlet of the compressor to direct the flow of refrigerant thereto, a second port fluidly connected to an outlet of the compressor to receive the flow of refrigerant therefrom, a third port, and a fourth port; a first fluid flow path extending between the third port of the reversing valve and a first port of the expansion device; a second fluid flow path extending between the fourth port of the reversing valve and a second port of the expansion device, the second fluid flow path including a first branch portion and a second branch portion arranged fluidly in parallel with the first branch portion; and a heat exchanger having a first plurality of fluid conduits and a second plurality of fluid conduits, wherein the first plurality of fluid conduits and the second plurality of fluid conduits provide parallel flow paths for refrigerant flowing along the first branch portion and wherein the first plurality of fluid conduits and the second plurality of fluid conduits provide a series flow path for refrigerant flowing along the second branch portion.
 2. The heat exchange system of claim 1, wherein the flow of refrigerant is directed along the first branch portion but not the second branch portion when the heat exchange system is operating in the air conditioning mode and wherein the flow of refrigerant is directed along the second branch portion but not the first branch portion when the heat exchange system is operating in the heat pump mode.
 3. The heat exchange system of claim 2, further comprising: at least one flow control device arranged along the first branch portion to allow the flow of refrigerant when the heat exchange system is operating in the air conditioning mode and to block the flow of refrigerant when the heat exchange system is operating in the heat pump mode; and at least one flow control device arranged along the second branch portion to block the flow of refrigerant when the heat exchange system is operating in the air conditioning mode and to allow the flow of refrigerant when the heat exchange system is operating in the heat pump mode.
 4. The heat exchange system of claim 1, wherein the heat exchanger comprises: a first fluid manifold arranged at an end of the heat exchanger; a second fluid manifold arranged at an end of the heat exchanger; and a third fluid manifold arranged at an end of the heat exchanger, wherein the first plurality of fluid conduits extend between the first fluid manifold and the second fluid manifold and wherein the second plurality of fluid conduits extend between the second fluid manifold and the third fluid manifold.
 5. The heat exchange system of claim 4, wherein the heat exchanger comprises a fluid port connected to the second fluid manifold, the flow of refrigerant passing through said fluid port when the heat exchange system is operating in the air conditioning mode but not when the heat exchange system is operating in the heat pump mode.
 6. The heat exchange system of claim 4, wherein the heat exchanger further comprises a fluid distributor arranged within the second fluid manifold and coupled to the fluid port connected to the second fluid manifold.
 7. The heat exchange system of claim 4, wherein the heat exchanger comprises a first cylindrical header tube containing the first fluid manifold and the third fluid manifold, and a second cylindrical header tube containing the second fluid manifold.
 8. The heat exchange system of claim 7, wherein the first fluid manifold and the third fluid manifold are separated by a baffle provided within the first cylindrical header tube.
 9. The heat exchange system of claim 4, wherein the heat exchanger comprises a first fluid port connected to the first fluid manifold and a second fluid port connected to the third fluid manifold, wherein the second fluid port operates as an outlet port for the flow of refrigerant in both the air conditioning mode and the heat pump mode and wherein the first fluid port operates as an inlet port for the refrigerant in the heat pump mode and as an outlet port for the refrigerant in the air conditioning mode.
 10. The heat exchange system of claim 9, wherein the heat exchanger further comprises a third fluid port connected to the second fluid manifold, the third fluid port operating as an inlet port for the refrigerant in the air conditioning mode.
 11. The heat exchange system of claim 10, wherein the heat exchanger further comprises a fluid distributor arranged within the second fluid manifold and coupled to the third fluid port.
 12. The heat exchange system of claim 4, wherein the first fluid manifold and the third fluid manifold are arranged at the same end of the heat exchanger and wherein the second fluid manifold is arranged at an opposite end of the heat exchanger.
 13. The heat exchange system of claim 4, wherein the first fluid manifold, the second fluid manifold, and the third fluid manifold are arranged at the same end of the heat exchanger. 